Apparatus for forming semiconductor chip packages

ABSTRACT

The present invention relates to an apparatus for forming semiconductor chip packages which is able to compensate for the flatness of substrates and the true straightness of edges of substrates, which substrates are inserted in molds in a forming process of semiconductor chip packages. According to the present invention, the semiconductor package strips excellent in surface flatness and side straightness of a substrate can be manufactured, because the thickness deviation and the side nonuniformity of a substrate can be compensated for in the resin molding process of the semiconductor package by use of a forming apparatus which comprises the individual cavity blocks, elastically mounted so as to float up and down, and the elastic pressing members, mounted on one end of the upper and lower chases. Therefore, the flashes owing to the defective substrates as encountered in a conventional art can be prevented, whereby mass production of semiconductor chips with the high precision and the excellent quality can be realized.

FIELD OF THE INVENTION

The present invention relates to an apparatus for forming semiconductorchip packages, and more particularly an apparatus for formingsemiconductor chip packages with a new construction, which is able tocompensate for the flatness of substrates and the true straightness ofedges of substrates, which substrates are inserted in molds in a formingprocess of semiconductor chip packages.

BACKGROUND OF THE INVENTION

Generally, semiconductor chip packages are manufactured by attachingsemiconductor chips on a lead frame of copper and then electricallyconnecting the semiconductor chips with wire. The semiconductor chippackages may be divided into the quad flat package (QFP), the pin gridarray (PGA) and the ball grid array (BGA) according to manufacturingmethods and characteristics of semiconductor chip packages.Particularly, the BGA packages which are direct mounting type packageswithout a lead frame so as to allows high integration, will be undergrowing demand in consideration of the technical characteristic of thesemiconductor industry which is in a trend of getting preciser.

The BGA packages use a substrate which is formed by laminating amultitude of thin resin sheets to a predetermined thickness throughadhesive and cutting the resultant lamination to have a proper width byusing an end mill. However, as the substrate mentioned above was formedof multi-layered resin sheets, it was difficult to obtain a uniformthickness. Besides, there was a disadvantage that the cutting face wasnot accurately straight.

The nonuniform thickness of a substrate and the poor straightness of acutting face as mentioned above cause a flash due to the molding resinwhich leaked out through uneven crevices between an upper and lowerform-imparting molds and a substrate at the time of moldingsemiconductor chip packages. FIGS. 1 and 2 show a flash 103 due to athickness error 105 of a substrate 100 at the time of moldingsemiconductor chip packages and a flash 102 due to a straightness error104 resulted from the cutting of a substrate 100.

The flashes in the molding process of semiconductor chips as explainedabove constitutes a serious cause for production of defective productsin the later cutting and packing stages in the course of producingsemiconductor chip packages. Therefore, in an effort to reduce thosethickness errors in substrate plates, there were employed, for example,such methods in which the corresponding parts of molds were replacedevery time of molding or respective substrates were classified based onthe thickness groups in order to compensate for the thickness differenceamong molds. However, these methods still resulted in thicknessdifference of 1-3 mils for each unit package, even when compensation wasmade by a cavity bar for each unit substrate, whereby the generation offlashes on individual semiconductor chips could not be avoided and delayin replacement entailed a big loss in productivity.

SUMMARY OF THE INVENTION

The present invention which was created to resolve the above-describedproblems of conventional art has the object to provide an apparatus forforming semiconductor chip packages with a new design, which isexcellent in evenness and straightness due to compensation for the errorin substrate thickness and the error in straightness of the substratesides cut or trimmed in a forming process of semiconductor packages, andis capable of preventing flash occurrence on substrates.

According to a characteristic of the present invention, there isprovided an apparatus for forming semiconductor chip packages comprisingupper and lower cavity blocks 30, 40 engaged together, with a pluralityof substrates 100 interposed, and upper and lower chases 10, 20 disposedaround said upper and lower cavity blocks 30, 40 and supporting themrespectively, one of said upper and lower cavity blocks 30, 40 beingformed with a plurality of cavities 44, characterized in that saidapparatus comprises a plurality of individual cavity blocks 50juxtaposed corresponding to individual substrates 100, said plurality ofindividual cavity blocks being manufactured discretely and positioned onthe side not having cavities 44, retainer members 52 engaged with saidindividual cavity blocks 50 through vertical penetration ofcorresponding chases 10 for allowing vertical floating of saidindividual cavity blocks 50 relative to the corresponding chases 10, andelastic members 54 disposed between said individual cavity blocks 50 andthe corresponding chases 10.

According to another characteristic of the present invention, there isprovided an apparatus for forming semiconductor chip packages comprisingupper and lower cavity blocks 30, 40 engaged together with a pluralityof substrates 100 interposed, and upper and lower chases 10, 20 disposedaround and supporting said upper and lower cavity blocks 30, 40respectively, wherein said apparatus comprises a first elastic pressingmember 60 rotatably hinged by a first pin onto a side of one of theupper and lower chases 10, 20 and formed with an inclined portion 62 onits inside tip, and a second elastic member 70 coupled by a second pinonto a mating side of the other chase 20 to be pressed inwardly throughcontact with said inclined portion 62 of said first elastic pressingmember 60 and provided on its inside surface with a flat portion 76 forcontacting an edge of one of the substrate 100.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1 and 2 are respectively a perspective view and a side elevationof a conventional substrate, particularly showing the flashes,

FIGS. 3 and 4 are respectively a front section and a side section of anapparatus for forming semiconductor chip packages according to anembodiment of the present invention, and

FIG. 5 shows an enlarged view of a major part of the present invention,as shown in FIG. 4.

DETAILED DESCRIPTION OF THE INVENTION

Now a preferred embodiment of the present invention will be describedwith reference to the accompanying drawings.

FIGS. 3 and 4 are a front section and an side section of a formingapparatus according to the present invention respectively and FIG. 5shows an enlarged view of a major part thereof. As illustrated, the sameas in an ordinary conventional apparatus for forming semiconductorpackages is the construction that the upper and lower cavity blocks 30,40 as well as a runner block 42 are joined together, surrounded by theupper and lower chases 10, 20, and cavities 44 are formed on the topsurface of the lower cavity block 40. However, the present invention hasa characteristic feature that the upper cavity block 30 is composed ofthe individual cavity blocks 50 which are individually manufactured andjuxtaposed corresponding to individual substrates 100. And theindividual cavity blocks 50 are constructed in such a manner that theycan float up and down in relation to the upper chases 10.

Specifically, each of the upper individual cavity blocks 50 is mountedin the upper chase 10 so as to be cleared 59 from it by a retainermember 52 of bolt type which pentrate vertically through the upperchaser 10 via a sleeve 58. And on the top part of the upper individualcavity block 50 where the retainer member 52 is fastened, there isformed a recess 56 in which an elastic member 54 like a disk spring isinterposed.

According to such a construction, because the height is controlledthrough an elastic vertical motion of the upper individual cavity block50 even if there exists the thickness deviation in the individualsubstrates 100 which are interposed between the upper and lower cavityblocks 30, 40, the thickness deviation in the substrates can becompensated for within the molds, if the elastic modulus of the diskspring as an elastic member 54 is properly set to within the allowanceof the substrate at the time of designing molds.

Although there was described in the above embodiment a case wherein anupper cavity block 30 is made of the upper individual cavity blocks 30corresponding to respective substrates, a lower cavity block 50 may becomposed of individual cavity blocks. In that case, a substrate 100should be placed upside down between the upper and lower cavity blocksso that the resin molding may be positioned correctly.

Another characteristic feature of the present invention will beexplained by referring to FIGS. 4 and 5. The first elastic pressingmember 60, which is formed with a inclined portion 62 on its inwardlower side, is rotatably mounted on one end of the upper chase 10 by afirst fixing pin 64. This first elastic pressing member 60 is turnedaway and returned back in an elastic manner by a spring 66, which isdisposed on one end part as seen in the drawings. The turning of theelastic pressing member 60 is regulated by a stopper 68 which mayconstitute a part of the upper chase 10 or a discrete member.

On a mating side of the lower chase 20 corresponding to theabove-mentioned first elastic pressing member 60, there is mounted thesecond elastic pressing member 70 rotatably about a second fixing pin74, which member is formed with an inclined portion 72 on its outwardupper side to be in contact with the inclined portion 62 of the abovementioned first elastic pressing member 60. On the lower one side ofthis second elastic pressing member 70, there is also disposed a spring78, so that the second elastic pressing member 70 may be elasticallyturned or returned back. The inner surface of this second elasticpressing member 70 comprises a flat portion 76 to contact the end sideof a substrate 100 which is positioned between the upper and lowercavity blocks 30, 40. Accordingly, at the instant when the upper andlower molds are engaged, the first elastic pressing member 60 which isnormally urged inward comes into contact with the second elasticpressing member 70 to press the latter inward, whereby the secondpressing member 70 presses the end side of the substrate 100 with itsinner flat surface 76. At this time, because the substrate 100 ofresinous material is in a pliable state due to the preheating at around175° C., the substrate 100 is pressed by the flat portion 76 on its endside so that the end side is smoothly trimmed to provide the substrate100 with an excellent straightness.

As a matter of course, a reverse arrangement in which the first elasticpressing member 60 is pin-coupled onto the lower chase 20 and the secondelastic pressing member 70 is pin-coupled to the upper chase 10 couldserve the same function of the present invention.

According to the present invention as explained above, semiconductorpackage strips which is excellent in surface flatness and sidestraightness of a substrate can be manufactured, because the thicknessdeviation and the side nonuniformity of a substrate 100 can becompensated for in the resin molding process of the semiconductorpackages by use of a forming apparatus which comprises the individualcavity blocks 50 elastically mounted so as to float up and down, and theelastic pressing members 60, 70 mounted on one end of the upper andlower chases 10, 20. Therefore, the flashes owing to the defectivesubstrates as encountered in a conventional art can be prevented,whereby mass production of semiconductor chips with the high precisionand the excellent quality can be realized.

What is claimed is:
 1. An apparatus for forming semiconductor chippackages, comprising:upper and lower cavity blocks (30, 40) engagedtogether with a plurality of substrates (100) interposed; upper andlower chases (10, 20) disposed around and supporting said upper andlower cavity blocks (30, 40), respectively; a first elastic pressingmember (60) rotatably hinged by a first pin onto a side of one of saidupper and lower chases (10, 20), said first elastic pressing member (60)being formed with an inclined portion (62) on an inside tip thereof; anda second elastic pressing member (70) coupled by a second pin onto amating side of the other of said upper and lower chases (20, 10) to bepressed inwardly through contact with said inclined portion (62) of saidfirst elastic pressing member (60), said second elastic pressing member(70) being provided with a flat portion (76) on a inside surface thereoffor contacting an end side of one of said substrates (100).